Some things that always struck me as odd before atheism
1. Every race and region had its own gods and goddesses, who all reflected
the cultural mores and behavior of the people that made them. Even Xenophanes and others notes this: Every place has gods and goddesses of their own social design. "If triangles had Gods, they would have 3 sides."
2. Noting this, how could anybody be a universalist with religion? Even supposing one were "true" that would just have made it true for that group of people. This also made the idea of missionary work very bizarre to me.
3. The first point and the second lead to the third:The provincialism of it all.
Why just one region producing religion for everything? Why only 1 Moses, 1 Son of God and 1 Muhammed? Why not 200 people all saying the same things in every region?
4. The most important thing in the religions are books which are meant to parsed and puzzled over by grandees. How can God have a perfect mind if he can't even reason simply? Why produce a "Holy Book" after several centuries of fractious debate in a time that predates mass literacy and the printing press?
Nobody has a problem with the Torah and Talmud and Koran and Bible taking centuries to make and then predating mass publication and mass literacy by well over 1000 years?